My invention comprises improvements in prior art transaxle designs, of the type disclosed in my prior U.S. Pat. Nos. 4,346,622 and 4,418,585. It comprises improvements also in the transaxle arrangement disclosed in Vahratian et al U.S. Pat. No. 4,368,649; Croswhite U.S. Pat. No. 4,224,837; Bookout U.S. Pat. No. 3,446,095; Moan U.S. Pat. No. 3,491,621 and Croswhite U.S. Pat. No. 4,452,099, each of which is assigned to the assignee of this invention. It comprises improvements also in U.S. Pat. Nos. 4,607,541 and 4,056,988.
Each of these prior art references describes a transaxle having a converter and a gearing system wherein the axis of the converter is situated in spaced, parallel relationship with respect to the axis of a driving differential for vehicle half shafts. In each case a drive chain or a torque transfer gear system is used to deliver torque from one axis to another prior to its distribution to a final drive and to a differential and axle assembly.
It is essential in transaxles of this type for the torque transfer elements to be arranged in such a way that a minimum axial spacing is required for the axial stackup dimensions. This permits packaging in a front wheel drive vehicle wherein the engine and transmission are situated in an engine and transmission compartment that is restricted in space because of vehicle styling requirements.
When torque multiplication gearing portions of the transaxle are situated on an axis parallel to and offset from the axis of the converter, the packaging considerations are different than they are when the torque transfer elements are situated on a common axis with respect to the axis of the converter and the engine. In an arrangement of the type shown in my earlier U.S. Pat. No. 4,418,585, the major torque transfer elements are situated on the torque output shaft axis rather than on the engine crankshaft axis so the torque delivery gearing is laterally offset or overlapping with respect to the engine crankshaft, thus reducing the overall axial dimensions of the transaxle and engine assembly. When the torque delivery gearing is located on a common axis with the converter and the engine, however, this overlapping and offset disposition of the gearing with respect to the engine cannot be accomplished. Thus the problem of reducing the overall stackup of the axial dimensions of the converter and the gearing, as well as the clutches, requires an alternate solution.
In prior art U.S. Pat. Nos. 4,224,837; 4,452,099; and 4,346,622 the gearing is located on a common axis but an undesirable elongation of the overall dimensions of the engine and transaxle assembly occurs. This problem is more pronounced in the arrangement of U.S. Pat. Nos. 4,224,837 and 4,346,622 than in the case of the gearing structure shown in U.S. Pat. No. 4,452,099 because in the design of the latter patent only the overdrive gearing is located on the converter axis while the multiple ratio torque multiplication gearing is located on a parallel, offset axis in common with the axis of the differential and axle assembly.
In each of the gearing systems shown in U.S. Pat. No. 4,346,622 a drive chain is used to transfer torque between one axis and the other. The drive chain, which serves as the torque transfer mechanism, is disposed between the torque multiplication gearing and the converter. The requirement that the location of the transfer drive be at this place necessarily increases the overall dimensions of the transaxle and engine assembly. Further, each of these gearing constructions of the prior art references has at least a portion of the clutch and brake system situated between the converter and the gearing. This exacerbates the space problem. In the case of U.S. Pat. No. 4,224,837 a torque transfer chain is located between the converter and a portion of the clutch and brake system. In the case of U.S. Pat. No. 4,346,622, the clutches and brakes are located between the converter and the torque transfer chain.